1. Field of Invention
The present invention relates to systems and methods for performing refractive laser surgery on the eye, and, more particularly, to such systems and methods that adaptively modulate sensed data on the basis of data from prior procedures.
2. Description of Related Art
In conventional refractive laser surgery a clinician typically modifies a prescription entered into the treatment system. Such modifications are based upon prior experience with outcomes achieved with that particular treatment system, and also upon experience with particular patient populations derived from, for example, demographic data. For example, a surgeon might enter a 2-diopter myopic treatment prescription for a patient diagnosed with 3 diopters of myopia if analysis of previous outcomes indicates a 50% overcorrection using this system for patients of a particular category. Such an empirical alteration of entered treatment parameters based upon previous experience is referred to as a nomogram adjustment. Nomograms are considered essential by the ophthalmic community because different clinicians employ different surgical techniques, operate under different environmental conditions, have distinct patient demographics, etc.
One method of obtaining nomograms is to enter desired correction parameters into a laser system, measure a patient's refractive state (or errors) before and some time after the procedure, and then determine the achieved change in refraction as a function of desired change in refraction. By computing the relationship between these desired and achieved corrections, a surgeon can generate a nomogram that defines those adjustments to the values entered into the laser system that will result in the best achieved outcomes. Typically, this nomogram consists of equations that define the values to be entered into the laser system as a function of the desired correction and a plurality of patient parameters including, but not limited to, age and a variety of diagnostic measurements.
A standard way of computing and applying these corrections (nomograms) is to perform at least-squares fit, or other trend calculation, to the achieved versus desired correction data. However, this approach does not account for noise in the data, and can result in the computation of nomograms that are overly aggressive, with corresponding sub-optimal outcomes.
Therefore, it would be beneficial to provide a system and method for improving the calculation and application of nomograms, and hence, outcomes, for use with refractive laser surgery.